Giant Hogweed and Wild Parsnip

Many plants can easily be mistaken for Giant Hogweed and Wild Parsnip, including Angelica, Cow Parsnip, and Queen Anne's Lace. Learn how to identify Giant Hogweed and Wild Parsnip:

Both Giant Hogweed and Wild Parsnip can be dangerous to touch. Review the Town of Oakville Safety Alert (pdf) and the Toxic Plants Caution Sign (pdf) for safety information.

Giant Hogweed

Giant Hogweed is a large, invasive plant that can grow up to six metres tall. It has a thick stem with reddish spots and large, cabbage-like leaves. Its white flower clusters and seed heads are distinguished by their rounded umbel shape and size of up to a metre across.

Giant Hogweed's sap contains chemicals that can cause skin to become hypersensitive to sunlight and erupt in painful blisters. If you see this plant, do not touch it. If you come in contact with the plant, you should thoroughly wash exposed skin with soap and water, and keep the affected area out of direct sunlight for at least 48 hours. If your skin reacts or becomes painful, seek medical attention.

The town has erected signs in areas where Giant Hogweed has been found. If you stay on established park paths and groomed trails on town property, you should not encounter Giant Hogweed. If you come across Giant Hogweed on town property, do not attempt to remove it. Instead, inform Service Oakville at 905-845-6601. They will notify the appropriate town staff who will confirm plant identification, report to Conservation Halton for tracking, and treat the area as appropriate.

The Town of Oakville partners with Conservation Halton to control Giant Hogweed with herbicide application. Find out more:

Wild Parsnip

Wild Parsnip is an invasive plant that can grow up to 1.5 metres tall, has a smooth single green stem 2-5 centimetres thick, and compound leaves with sharply toothed leaflets that resemble mittens. It can be distinguished from its look-alikes during flowering season by its yellowish-green umbrella-shaped flower clusters 10-20 centimetres across.

It was introduced from Europe as a food crop for its edible root, but the sap of the plant may cause skin irritations, burns or blisters. As with Giant Hogweed, contact with this plant should be avoided. Thoroughly wash with soap and water immediately after exposure to the sap, avoid direct sunlight on the affected area and seek medical attention should you have a reaction to the sap.

Wild Parsnip is present in most open and naturalized areas throughout town. Its abundance makes control almost impossible. The town is limiting control treatment to groomed park space and areas within two metres of granular and paved trails and walkways. Extreme caution should be exercised if using foot trails not maintained by the town and in all naturalized spaces.